Parallel Kinetic Resolution of Acyclic γ-Amino-α,β-unsaturated Esters: Application to the Asymmetric Synthesis of 4-Aminopyrrolidin-2-ones

Abstract

Conjugate addition of a 50:50 pseudoenantiomeric mixture of lithium (<i>R</i>)-<i>N</i>-benzyl-<i>N</i>-(α-methylbenzyl)amide and lithium (<i>S</i>)-<i>N</i>-3,4-dimethoxybenzyl-<i>N</i>-(α-methylbenzyl)amide to a range of racemic acyclic γ-amino-α,β-unsaturated esters (derived from the corresponding α-amino acids) effects their efficient parallel kinetic resolution, allowing the preparation of enantiopure β,γ-diamino esters. The β,γ-diamino ester products of these reactions are readily converted into the corresponding substituted 4-aminopyrrolidin-2-ones via <i>N</i>-debenzylation and cyclization